The power required to operate a rotorcraft may substantially change during the flight path of the rotorcraft. A rotorcraft typically requires substantially more power during a hover, compared to when the rotorcraft is traveling forward at a moderate airspeed. For example, as the rotorcraft is slowed to a landing, the increased power requirement at hover can consume all the power that the engine(s) have available (particularly with a heavy aircraft at a hot temperature and high altitude environment) causing loss of rotor rpm, an uncontrolled descent, and possibly a crash landing. Furthermore, the exact power required during hover is affected by a variety of variables, such as pressure altitude and air temperature.
Typically, a pilot will make pre-flight calculations to predict if the rotorcraft will have adequate power available to make an approach to hover. The pilot will typically make these pre-flight calculations by collecting information from several sources. The calculations may include an estimate of the power required by the aircraft to fly at hover at a specific location. Another calculation may include an estimate of the power available by the aircraft at hover at the specific location. The power available and power required calculations are then compared to in order to predict sufficient power margin.
Typically, the aforementioned power available and power required calculations are performed by the pilot on the ground in consultation with relevant performance charts in the rotorcraft flight manual. If the expected flight involves performing a hover landing at a landing site that is different than the departure site, then the pilot must make educated guesses regarding certain conditions at the time of landing. For example, the pilot will typically make an educated guess in predicting the approximate weight of the rotorcraft at the time of landing. In addition, the pilot will make an educated guess regarding the predicted air temperature and pressure altitude at the landing site. Each of these variables can be difficult to accurately predict.
There are many potential error opportunities due to the pilot having to read one or more charts, as well as make predictions regarding future flight conditions and atmospheric conditions. Furthermore, pilots typically are very conservative in order to allocate margin for any calculation errors. As a result, many rotorcraft are not fully utilized as pilots protect themselves and passengers from small but consequential errors and in-flight changes in the predicted variables (aircraft weight, outside air temperature, and pressure altitude). For example, a rotorcraft may make two separate flights transporting passengers from a departure site to a destination site when in fact the rotorcraft was fully capable of performing the task in a single flight. Such underutilization of rotorcraft cost rotorcraft operators an enormous amount of time and money over the life of a rotorcraft.
Although the developments in rotorcraft flight instrumentation have produced significant improvements, considerable shortcomings remain.
While the system of the present application is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the method to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the application as defined by the appended claims.